1. Field of the Invention
The present invention relates to a honeycomb structure and a method for manufacturing the same. The present invention more particularly relates to a honeycomb structure functioning as not only a catalyst carrier but also a heater when voltage is applied, thereby it can save energy to be applied thereto at the time of purifying exhaust gas. In the other words, the present invention is directed to an energy-saving honeycomb structure equipped with heater function therein. The present invention further relates to a method for manufacturing such a honeycomb structure with great easiness.
2. Description of Related Art
Conventionally, a cordierite honeycomb structure having a catalyst loaded thereon has been used for treating hazardous substances in exhaust gas emitted from an automobile engine. It is also known that a honeycomb structure formed of a silicon carbide based fired body is used for purifying exhaust gas (see, e.g., Patent Document 1).
In the case of treating exhaust gas with a catalyst loaded on a honeycomb structure, it is necessary to raise temperature of the catalyst to predetermined temperature. However, there is a problem that exhaust gas is not sufficiently purified due to low temperature of the catalyst at the time of engine start.
Therefore, a study was made on a method for heating exhaust gas by providing a metal heater on the upstream side of a honeycomb structure having a catalyst loaded thereon (see, e.g., Patent Document 2).
There is also proposed to use a ceramic honeycomb structure as a “heatable catalyst carrier” (see, e.g., Patent Document 3).
[Patent Document 1] JP 4136319
[Patent Document 2] JP 2931362
[Patent Document 3] WO 2011/125815